[PATCH v4 11/15] cryptodisk: Replace some literals with constants in grub_cryptodisk_endecrypt.

[Glenn Washburn]

This should improve readability of code by providing clues as to what the
value represents. The new macro GRUB_TYPE_BITS(type) returns the number of
bits allocated for type. Also add GRUB_TYPE_U_MAX/MIN(type) macros to get
the max/min values for an unsigned number with size of type.

Signed-off-by: Glenn Washburn <development@efficientek.com>
---
 grub-core/disk/cryptodisk.c | 13 +++++++------
 include/grub/types.h        |  5 +++++
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c
index 473c93976..31b73c535 100644
--- a/grub-core/disk/cryptodisk.c
+++ b/grub-core/disk/cryptodisk.c
@@ -284,22 +284,23 @@ grub_cryptodisk_endecrypt (struct grub_cryptodisk *dev,
          iv[1] = grub_cpu_to_le32 (sector >> 32);
          /* FALLTHROUGH */
        case GRUB_CRYPTODISK_MODE_IV_PLAIN:
-         iv[0] = grub_cpu_to_le32 (sector & 0xFFFFFFFF);
+         iv[0] = grub_cpu_to_le32 (sector & GRUB_TYPE_U_MAX (iv[0]));
          break;
        case GRUB_CRYPTODISK_MODE_IV_BYTECOUNT64:
-         iv[1] = grub_cpu_to_le32 (sector >> (32 - dev->log_sector_size));
+         iv[1] = grub_cpu_to_le32 (sector >> (GRUB_TYPE_BITS (iv[1])
+                                              - dev->log_sector_size));
          iv[0] = grub_cpu_to_le32 ((sector << dev->log_sector_size)
-                                   & 0xFFFFFFFF);
+                                   & GRUB_TYPE_U_MAX (iv[0]));
          break;
        case GRUB_CRYPTODISK_MODE_IV_BENBI:
          {
            grub_uint64_t num = (sector << dev->benbi_log) + 1;
-           iv[sz - 2] = grub_cpu_to_be32 (num >> 32);
-           iv[sz - 1] = grub_cpu_to_be32 (num & 0xFFFFFFFF);
+           iv[sz - 2] = grub_cpu_to_be32 (num >> GRUB_TYPE_BITS (iv[0]));
+           iv[sz - 1] = grub_cpu_to_be32 (num & GRUB_TYPE_U_MAX (iv[0]));
          }
          break;
        case GRUB_CRYPTODISK_MODE_IV_ESSIV:
-         iv[0] = grub_cpu_to_le32 (sector & 0xFFFFFFFF);
+         iv[0] = grub_cpu_to_le32 (sector & GRUB_TYPE_U_MAX (iv[0]));
          err = grub_crypto_ecb_encrypt (dev->essiv_cipher, iv, iv,
                                         dev->cipher->cipher->blocksize);
          if (err)
diff --git a/include/grub/types.h b/include/grub/types.h
index 495c86bb1..b57acc3b1 100644
--- a/include/grub/types.h
+++ b/include/grub/types.h
@@ -72,6 +72,8 @@
 # endif
 #endif
 
+#define GRUB_TYPE_BITS(type) (sizeof(type) * GRUB_CHAR_BIT)
+
 #ifndef __CHAR_BIT__
 #error __CHAR_BIT__ is not defined
 #elif __CHAR_BIT__ != 8
@@ -159,6 +161,9 @@ typedef grub_int32_t        grub_ssize_t;
 #endif
 # define GRUB_LONG_MIN (-GRUB_LONG_MAX - 1)
 
+#define GRUB_TYPE_U_MAX(type) ((2 * ((1ULL << (GRUB_TYPE_BITS (type) - 1)) - 
1)) + 1)
+#define GRUB_TYPE_U_MIN(type) 0ULL
+
 typedef grub_uint64_t grub_properly_aligned_t;
 
 #define GRUB_PROPERLY_ALIGNED_ARRAY(name, size) grub_properly_aligned_t 
name[((size) + sizeof (grub_properly_aligned_t) - 1) / sizeof 
(grub_properly_aligned_t)]
-- 
2.27.0